HIGH WITHSTAND-VOLTAGE VOLTAGE REGULATOR WITH RESET FUNCTION
S-87x Series
Rev.7.2_00
2. Load transient response characteristics due to load current fluctuation
An overshoot and an undershoot are caused in the output voltage if the load current is changed from
50 μA to 40 mA while the input voltage is kept constant. Figure 31 shows the output voltage fluctuation
due to a change in the load current. The measuring circuit is shown in Figure 32 for reference. The
latter half of this section describes ringing waveform and parameter dependency.
40 mA
50 μA
Load current
Overshoot
Output Voltage deviation
Undershoot
Figure 31 Output voltage fluctuation due to a change in the load current
S-87x
Series
VIN
VOUT
*1
*3
*2
+
+
R1
CL
R0
VSS
−
10 μF
−
Power
supply
Oscilloscope
10:1 probe
VOUT [V]
50 μA
*1. R1=
*2. R0=
[Ω]
[Ω]
VOUT [V]
40 mA
*3. AL electrolytic capacitor
Figure 32 Measuring circuit
Table 22 Parameter dependency due to load current fluctuation
Method to decrease Method to decrease
Series
Parameter
Load current (IOUT
Load capacitance (CL)
Power supply voltage (VIN)
Temperature (Ta)
Conditions
overshoot
undershoot
S-8750xxx,
S-8730xxx
)
10 to 60 mA, CL=10 μF
1 to 47 μF, IOUT=40 mA
(VOUT+1) to 24 V
Decrease
Decrease
Increase
Increase
Increase
Increase
−40 °C to +85 °C
Low temperature
Low temperature
38
Seiko Instruments Inc.
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